1. Field of the Invention
The present invention relates to the tracing of microwords being processed in a computer system.
2. Description of the Related Art
In many computer systems the feature of tracing is used for storing the operations of sequential microwords as they are processed by the computer system to allow error analysis of errors that occur during processing. To this end, the addresses of all processed microwords are sequentially stored in a random access memory which is generally designed to store a plurality of addresses. The address of the microword being processed is stored over the oldest address in the random access memory after the random access memory has been initially filled.
Many programs use timeout loops and software delays. These timeout loops or software delays are a series of micro-instructions which either provide a pause in the operation of the program as indicated by a delay loop, or a period of time for an event to be sensed by the program as provided by a timeout loop. When a timeout loop or delay loop is used the number of resulting addresses stored can be very large and can fill, or substantially fill, the random access memory. This is an undesirable feature of the timeout or delay loop because if an error occurs after the timeout loop or delay, the past history of the operation of the computer might be lost and therefore hamper the debugging of the error state of the system.